A fuel cell electrolyte comprises: a basic polymer; an organic phosphonic acid expressed by the following general formula (1); and a hydrolyzable phosphate compound expressed by the following general formula (2): ##STR00001## where R represents an alkyl, aryl, acyl, amino, phosphonic group or a derivative of the functional group, and n is 1 or 2, and R represents an alkyl or alkoxyalkyl group, and n is 1 or 2.